Device-to-device (D2D) communication enables a user equipment (UE) to directly communicate with another UE in the vicinity thereof. Compared to existing communication technologies involving base stations (ENB), D2D communication facilitating easy frequency reuse between proximate UEs requires a smaller amount of radio resources and can be more efficient in the usage of radio resources. As D2D communication enables one UE to obtain information about nearby UEs, the obtained information can be used to create new services including advertisement services and social networking services (SNS). Currently, various efforts are underway to support D2D technologies, such as transmission and reception schemes for discovery signals to discover proximate UEs and schemes for synchronization in D2D communication, in the Long Term Evolution-Advanced (LTE-A) system.
FIG. 1 depicts a situation where D2D communication is supported in a cellular system.
In FIG. 1, the ENB 101 manages UEs 103, 104 and 105 remaining in the coverage of its cell 102. The UE 103 and the ENB 101 may perform cellular communication via a UE-ENB link 107; the UE 104 and the ENB 101 may perform cellular communication via a UE-ENB link 108; and the UE 105 and the ENB 101 may perform cellular communication via a UE-ENB link 109. Here, when D2D communication is possible between the UE 103 and the UE 104, the UE 103 and the UE 104 may directly exchange information via a D2D link 106 without passing through the ENB 101. However, if the radio resources used by the D2D link 106 for D2D communication between the UE 103 and the UE 104 are identical to those used by the link 109 for cellular communication between the UE 105 and the ENB 101, cellular communication and D2D communication cannot be correctly performed owing to interference therebetween. Hence, when D2D communication uses a cellular mobile communication system such as the LTE system, for correct operation of cellular communication and D2D communication, resources used by D2D communication may be separated from resources used by UEs using the existing cellular communication system.
As such, it is necessary to provide a method and apparatus that enable efficient usage of transmission resources for D2D communication.